Foreign Secretary William Hague has called for allegations of irregularities in Russia's presidential elections to be "thoroughly investigated".

But the Foreign Secretary made clear he did not want the issue to get in the way of Britain's relations with Moscow, saying he hoped to work with the Russian government to develop a "stronger and deeper partnership" between the two countries.

International election monitors from the Organisation for Security and Co-operation in Europe (OSCE) have criticised Sunday's ballot which returned Vladimir Putin for a further six years in the Kremlin.

The result sparked protests in Moscow where riot police dispersed and detained hundreds of demonstrators attempting to occupy a central square on Monday night.

The OSCE monitors gave a "negative assessment" to the vote count in one-third of the polling stations they visited. They said broadcast media was "clearly biased" in Mr Putin's favour, failing to provide fair coverage of other candidates.

Prime Minister David Cameron pointedly avoided congratulating Mr Putin on his victory when the two leaders spoke by telephone. But the two leaders agreed on the need to develop a "stronger relationship" despite "differences and areas of concern".

In a statement released by the Foreign Office in London, Mr Hague said: "I note the preliminary assessment of the OSCE/ODIHR (Office for Democratic Institutions and Human Rights) election observation mission of the Russian presidential elections.

"Overall, while the mission gives a positive assessment of voting on election day, it identifies problems with counting at some polling stations, unequal campaign conditions and limitations on voter choice. These issues should not be overlooked.

"A Russia with greater political freedoms, including the registration of political parties, freedom of assembly and freedom of the media, is in the interests of Russians and of the wider world. All allegations of electoral violations should now be thoroughly investigated."

Mr Hague added: "It is in Britain's interests to develop a stronger and deeper partnership with Russia by addressing the obstacles to the relationship so that we can extend our political and trade engagement. We look forward to working with the Russian government to do this."